Electric welding apparatus.



No. 837,296. PATENTED DB0. 4,1906. W. M. FULTON & J. 3; BROWN.

ELECTRIC WELDING APPARATUS.

APPLICATION FILED JUNE 23. 1904.

2 SHBETSSHEET 1 1! nvcmors N01 837296. PATEN'll-JJ) DEC, 4, 1906.

W? M. FULTON & J. s. BROWN. ELEGTRIG WELDING APPARATUS.

APPLIGATION FILED JUNE 23,1904.

2 SHEETS-SHE.BT 2

3,3 Jm cntors A witnesses g nrrnn srnr gas PATENT @FFIillE.

VVESTUN M. FUL'lON AND JOHN S. BROWN, 0F KNOXVILLE, TENNESSEE, ASSlGNORST THE FULTON COMPANY, OF KNOXVILLE, TENNESSEE,

A CORPORATION OF MAlNE.

ELECTRi WELDlNG: QF'PARATUEQ Application filed June 23.

To roll Ii /ham it may (-(HIJZVP/b.

Be it known that we, \Vns'ros M. FI'LTON and JOHN S. BnowmoiKnoxville,Tennessee, T have invented a new and useful Electric 5 WeldingA'p aratus, which invention 1s fully set forth in t 1e followingspecification.

This invention relates generally to a method of electric welding andapparatus for carrying out such method, but especially to electricwelding of thin sheet metal.

In electrically welding sheet metal it is customary to lap the edges tobe welded and pass them between two conducting rolls,

which constitute electrodes, and to heat the 1 lapped edges by a currentof high amperage and low voltage. In the application of this method tothin sheet metal serious dilliculties have heretofore been experiencedin main: taining a uniform heat at the point where the welding is beingeffected. This inability to properly control the heating effect at the:jllnC'tlOIl of the thin metal neev produces irregular welding, evenburning through the metal at some points, while at other points notenough heat is generated to cause the metal to weld. For these reasonselectric welding has not been successfully applied t6 thin. sheet metal.The irregular heating of the thin metal, we have discovered, is due tothe varying resistance offered by the scale, which 'adheres tightly tothe rolls, which latter constitute the electrodes through which thecurrent passes. As the metal is heated by the electric cur rent andpressed together by the rolls there is formed a slight amount of scale,which adheres tightly to the surfaces of the rolls where they come intocontact with the metal, and as this scale collects it forms a thin i ilmor coating on the eriphery oi the rolls, which offers a relative y highresistance to the electric current. Furthermore, this coating is ofuneven thickness, and its resistance to the flow of current accordinglyvaries successive points on the periphery of the rolls come intocontactwith the metal to be welded. Nhile these inequalities may not be ofmaterial consequence in welding thick metal, they are of utmostconsequencein welding very thin metal, as will be apparent from a closerconsideration of the two cases. w Suppose, for example, it is proposedto weld together the overlappingedges o'f'sheets of No. B. 8: S. gageBesse- Specification of Letters Patent.

Patented Dec. 4, 1906,

1904. Serial No 213,864..

nier steel. This steel is .005inchinthickness, which would'givc a totalthickness of .0]. inch at the sean'is where themetal is lapped. Supposethat when the seamsare first started through the rolls the resistance ofthe metal is .05 inicrohni and the resistance at the surfaces in contactis microhni, makings total resistance between the rolls of 0.2llii(I()llI1l. As the welding proceeds and the coating of scaleaccumulates upon the rolls, suppose the resistance at the surface ofcon-- tact between the rolls and the metal to in crease to .35 microhin,the resistance of the metal remaining .05 as at first. This would give atotal resistance of 0.4. inicrohm 5 between the rolls, just double theoriginal totai resistance: This would reduce the electric current fiftyper cent, the voltage 1- reinaining constant. Next consider the case ofthicker metal. Suppose. for examplathat I ing edges of sheets of No. 2B. & S. gage g essemer steel. This metal is about fifty times as thickas No. 36 gage metal, and consequently its resistance would be microhmon the supposition that No. 36 is .05 microhm. Let the resistance at thesurfac of contact be .15 inicrohm at the beginning of the weld, as inthe case of the thin metal. This would give a total resistanceofInicrohms between the rolls. Now let the metal he drawn between therolls, as before, and suppose, as in the case of the thin metal, thecoating of scale on the surface of the rolls increases the resistance onthe surface of contact to .35 microhni, the resistance of the thickmetal remaining 2.5 microlnns- This would give a resistance of 2 .85microhms between the rolls, an increase of only about seven and one-halfer cent over the original total resistance. Tiiis would reduce thecurrent only seven per cent, the voltage remaining constant. In otherwords, since the resistance offered to a given electric current by a.thin piece. of metal is less than that, oll'ered by a thicker piece ofthe same kind of metal, it is evident that any given variation inresistance it" produced in each case by the 311111 ise will produce agreater change in the electric current in the thin metal than in thethick. it is thus apparent from a mathematical standpoint that thethickness oi the metal to he welded-isan allimportant factor in thepresent pioeess oi it is proposed to weld together the overlap electricWelding, and We have found this distinction a vital one in actualpractice. Recalling that according to a well-known physical law the heatproduced by electricity is directly proportional to the product of theresistai'ice multiplied by the square of the current, it necessarilyfollows from what has been said above that there must be markedvariations in the heat developed as the seam is drawn along, between therolls. In order, therefore, to effect the Weld at all points along theseam, the voltage must begreat enough to produce the requisite heat atthe points of greatest resistance. Hence when points of least resistanceare reached the heat becomes excessive. After a very slight film ofscale has collected on the rolls this inequality in heat becomes somarked that holes are burned through the metal at some points, While atothe it is not welded, thus rendering the process worthless for Weldingthin metal. Furthermore, this irregular heat softens the rolls in spotsand very soon'causes them to wear unevenly at the periphery and destroysuniform. contact with the metal.

Our object is to overcome the difliculties above referred to, andthereby successfully electrically weld together all kinds of thin. metalsheets, strips, or ed To that end our invention consists, broadlystated, in effecting and producing means for effecting an approximatelyuniform resistance to the electric current by continuously rci'i'ioving;the scale from the surface of the electrodes and dressing of polishingsaid surfaces to evenness, so to eontirniously pre serve uniformity ofcontact with the metal to be welded. Broadly statcd,'thc means employedfor this purpose an abrasion device preferably in the form of a drivenroll acting against the moving surface of the electrode to constantlymaintain the same in such condition as to afford uniform desistance tothem went.

The invei'itive idea involved may receive various mechanicalexpressions, some of which are shown in the accompanying dravx V ings,which are designed merely to assist in the description of the inventionand not as defining the limits tl'iereofi Figure l is an elevation.Figs. 2- and 3 are an clmatlon and a plan view showing: a niodifi ation.Fig. i a cross-section on. the line 1- 4 of Fig. l. the adjustablecross-head Fig. 6 is a side elevation, Fig. 7 a bottom view, and Fig. 8an end View. illustrating: a modif vation of the means for driving; andadjusting the cleaning-roll. Figs. 9 and i show in elevation an end viewof a further modification. Fig. 11 illustrates means for rotating theelectrode and the cleaning-roll, and Fi 12 shows a stationarycleaning-blade insipid of a cleanii'ig-roll.

:ilexible bar Fig. is a detail of Referring to Figs. 1, 2, 3, i, and 5,electrodes 1 2 of suitable metal, such as copper, are rcvolublysupported in forks 3 4 of conductingerms 5 6. In juxtaposition to theelectrodes 1 2 we place suitable abrasion devices for removing the scalefrom the electrodes, which may be preferably supported in the same arms3 i as support the electrodes. Said devices are preferably in the formof dressing or polishing rolls or brushes 7, made of any approvedmaterial which will remove scale and act to true or dress the surface ofthe electrodes, such as carborunduni wheels or still. wire brushes.Rotary motion is imparted to rolls '7 7 by means of a cord and pulley 8In order to adjust the polishing-rolls 7 7 to the electrodes as theybecome abraded, the prongs 3 4 are provided with slots and 11, Fig. 4:,cut in their ends, and prong 4 also has a slot 12, which forms anopening through which the spindle '13 of roll 7 projects. Roll '7 ismounted in a U- shaped cross-head 14, which slides in slots 10 and 11.An end piecc-15 is bolted to the ends of prongs 4 5 and has passingthrough it a screw 16, which screws into the cross-head 14. The V-pulley9 is fastened on the end of spindle 1.3, and a cable 8 drives the pulleyfrom any convenient source of power. By means of screw 16 the pressureof polishing roll 7 upon Welding-roll 2 is regulated. lVhile the metalto be welded is passed under roll 2 roll 7 is driven at a high. speedand dresses the surface of roll 2, keeping it bright and true.

Figs. 6, 7, and 8 illustrate a modified means for mounting and adjustingthe polishing and cleaning roll 7. Two arms 17 are bolted to the prongsi 5 of conducting-arm 6. A rod i8 passes through their outcr ends, andupon one end of this rod is mounted a small pulley 9, fastened on theface of a gcarwheel 19, free to turn on rod 1%} as an axis. On rod 123and between arms 17 is pivoted a pronged arm LO, which carriesclcanii'ig-roll '7. The small pinion 121 on one end of the spin dieshaftof roll 7 meshes with gear-wheel ii). A 22 bolted to the lower end ofarm 2!) and has a screw 23 passing;- through the opposite end, and thescrew rests upon. arm 17. By turning the screw the pressure ofclouning-roll 7 against welding-roll 2 is regulated. A. cable drivespolicy 0, gearwhcel 19, pinion 21, and elcaning-roll 7.

lit is sometimes desirable to have the clean ing-q'oll move back andforth across the face of the welr'iing-roil in a direction parallel tothe axis of the roll while it is being, cleaned This may be accomplishedas indicated in Figs. 9 and 10. The pinions 2., and 24 have the samenumber of teeth, while the gear- Whcel 25 has one more tooth thangear-wheel 26. Pinion 23 is fast on the end of the spindle-shaft ofclcaningwoll 7 vhile pinion 24 is loose thereon. These pinions haveeccentric ceases turn on the end of a rod 18, as explained in Figs. 6,7, and 8. Gear-wheels and 26 are driven by a cable which passes aroundpulley 29. Since wheel 25 has one more tooth than. I

wheel 26, it is'evident that for each complete revolution of thesegear-wheels pinion 23 will i turn farther than pinion 24 by one tooth.This causes the eccentric/hubs 23 and 24 of these pinions to slide uponeach other and alternately assume the'positions indicated in Figs. 9 and10, thereby carrying cleaningroll 7 to the extreme right in Fig. 9 andto the extreme left in Fig. 1Q.

When it is desired to drive the weldingroll as well as thecleaning-roll, the arrangement shown in Fi 11 may be employed. As hereillustrated, the shaft of the welding-roll 2 is provided with a sprocketwheel and communicates motion to the polishingroll 7 through a train ofgears a l) c d e.

While we prefer to use a cleaning and dressing roll as the cleaningdevice for removing the scale and trning the surface of the electrodes,we do not limit such means. It is within the scope this in-- vention toemploy an suitable means to clean or dress the sur ace of the el tradewhich will efl'ect the results specified and Whether one of theelectrodes is revoluble and the other stationary or Whether both arerevoluble. In Fig. 12 a stationary abrasion device is illustrated forremoving the scale, and said means consists of a tool 31, suitablymounted in a tool-post 32, pressed by a spring 33, which holds the toolto its work. The

roll may then be driven by a worm v34 and worm-gear 35.

In operation the thin sheet metal, such as No. 36 B. 8: S. gage Bessemersteel, is lapped at the edges, as indicated in Fig. 1 at 36 and 37, andinserted between the electrodes 1 and 2 and then heated to a weldingtemperature by the passage of a suitable current. Vl'hile the metal issubjected to this operation the cleaning and polishing rolls 7 arerotated while pressed against the electrodes. rolls are rotated atgreater surface speed than the electrodes which are firmly pressedagainst the work. Fresh surfaces of the electrode are thus applied tothe metal sheets and a uniform resistance secured at the contact of thetwo surfaces, thereby producing a uniform heating and effecting aperfectlywelded union.

l/Vhat is claimcd is 1. In an electric welding apparatus, thecombination of a revolublc electrode adapted to bear against the workand through which .The

welding current passes to the latter, and means for maintaining thecontact-surface of sa1d electrode of approximately uniform conductivity.

, 2. In an electric welding apparatus, the combination of a revolublcelectrode adapted to bear against the work and through which weldingcurrent passes to the latter, and

means for removing scale from the contactsurface of said electrodeduring its operation. 3. in an electric welding apparatus, the

combination of a revoluble electrode ada ted to bear against the workand through w rich welding current passes to the latter, and means fordressing the contact-surface 9 said electrode during its operation.

4. In an electric welding apparatus, the combination of a revolubleelectrode adapted to bear against the work weldin current passes to thelatter, and means or continuously dressing the c ontactsurface of saidelectrode during its operation to maintain said contact-surface ofapproXimately uniform conductivity.

5. In an electric Welding apparatus, the combination of a revoluhleelectrode ada ted to bear against the worlr and through w ich Weldingcurrent passes to the latter, and an abrasion device acting upon thecontact-surface of the electrode.

6.111 an electric welding apparatus, the

combination of a revolu ble electrode ada ted to bear against the workand through w ich welding current passes to the latter, and ar abrasiondevice continuously acting upon the contact-surface of the electrodeduring its operation. l

7. In an electric welding apparatus, the combination of a revolubleelectrode ada ted tobear against the work and through w 'ch weldingcurrent passes to the latter, a rotatable abrasiorni'oll bearingagainstthe contact-sunace of the electrode, and means for rotating saidabrasion-roll at a different surface speed from that of the electrode.

8. In an electric welding apparatus, the combination of a revolubleelectrode adapted to bear against the work and through which a weldingcurrent passes to'the latter, means and throughir'vhich for dressing thecontact-surface of said elec- 4 trode during its operation, and meansfor adjusting the same to the electrode 9. In an electric weldingapparatus, the combination of a revoluble electrode adapted to bearagainst the work and through which a welding current passes to thelatter, an abrasion-roll bearing against the contactsurface of theelectrode, means for rotating the roll, and means for adjusting the sameto the electrode.

10. "In an electric welding apparatus, the combination of a revolubleelectrode adapted to bear against the Work and through which a weldingcurrent passes to the latter, an

to beer against the work end through w 'ch I a passes to the letter, anabrasion-roll, a resilient member normally I holding the roll againstthe electrode, means for adjusting the tension of said resilient member,and while the latter bears against the electrode.

In testimony -whereof we have signed our names to this specification inthe presence of two subscribing Witnesses.

WESTON M. FULTON. JOHN S BROWN,

Welding current Witnesses:

V5 C. HAZEN, C. A. MORSE.

means ior rotating the roll 20

